LXDE, TDE and KMail - can I achieve what I would like to do?

My husband's desktop died pretty conclusively at the beginning of teh mirror outage. Not knowing about the outage, I set out to install Squeeze + TDE. Without success, of course. I tried David's offering, which I liked very much and had help from several people on this list, but had not succeeded in getting it all running properly when my husband came home. So I installed LXDE so that he could use Thunderbird to read his emails. He has fallen for the speed of LXDE, and, for once, doesn't mind having to work differently. He wants to keep LXDE. I therefore have a lot of TDE dependencies, but no actual TDE packages. 1) If I install the rest of TDE at this stage, so that it is there if needed, will it impact at all on LXDE's speed of booting up and shutting down? I had been intending, as part of the reinstall, to move him from Thunderbird to KMail. In KMail, it is easier to remove virus-laden emails, before he sends them on to Windows using friends, without damaging or altering other emails. And I know it a lot better, and can more readily answer questions. 2) Would using Kmail slow LXDE down at all? I have so far failed to work out a method for Peter to be able to get his emails in KMail without inputting a password. One used to be able to store the necessary login details and passwords in KMail, as one can in Thunderbird. For a while now, that has not been possible, and one has to go via KWallet, which demands a password. 3) Is there a workaround which would allow KMail to download the email from Gmail without any password being input?? One method would be to go back to using the ISP's POP3 server, instead of going via Gmail, as I have for a while now. But I would like to be able to continue sending his emails via Gmail. And log-in details would then need to be saved somewhere. Thanks, Lisi